George O'Brien

According to IMDb, George O'Brien "was the son of the San Francisco Chief of Police who became a college athlete. He was the Heavyweight Boxing Champion of the Pacific Fleet during World War I. In the early 1920s, George wound up in Hollywood where he worked as a stuntman and part time actor... O'Brien served in the US Navy in World War I, and was decorated several times for bravery under fire." [1]